The present invention relates to a dot matrix printer comprising a printing head movable parallel to a writing platen for selectively printing dots on a writing medium disposed on the platen and a line-spacing device comprising a toothed wheel coupled to the platen and a pawl for intermittently rotating the wheel to advance the writing medium between two successive lines of printed dots.
Various printers of the type mentioned are known; in one of these the printing head is moved by a cam rotating about an axis perpendicular to the writing cylinder. Line spacing is obtained by means of a screw with a varying pitch which is solid with the cam and engaged with a toothed wheel coupled to the cylinder by a transmission gear. Such a printer proves to be very cumbersome for use with small computers and, because of the numerous moving parts, it is very noisy. Furthermore the line-spacing device includes a friction clutch for disengaging the line-spacing device to allow the paper tape to be advanced manually.
The object of the present invention is to provide a dot matrix printer which is very compact, and silent, and has few moving parts and is such as to allow the paper to be advanced manually without the use of additional devices.